Nutrient dynamics and phytoextraction in soils receiving long-term manure application

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Agomoh, Ikechukwu Vincent
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Inclusion of dried distillers grains with solubles (DDGS) in cattle diets may influence the release of plant-available nitrogen (N) from the resulting manure (DGM) relative to manure from cattle fed a regular grain diet (RM). This may be further exacerbated by the use of construction and demolition waste (CDW) components as bedding in beef cattle feedlots. Laboratory and greenhouse experiments were conducted to determine the effects of RM and DGM containing CDW or peat moss on canola (Brassica napus L.) growth, N uptake and the mineralization of N in a Black Chernozem and a Brown Chernozem. The presence of CDW in DGM and RM manure reduced cumulative dry matter yield (DMY) and plant N uptake relative to manure without CDW, while the presence of peat increased DMY and N uptake. Results from the two experiments showed that the addition of CDW decreased organic N mineralization, which may necessitate the application of synthetic N fertilizer to supplement N from CDW-amended DGM and RM manure. Nitrogen mineralization in the DGM- and RM-amended Black Chernozem followed mixed first-order and zero-order kinetics. In general, more organic N was mineralized from RM and DGM at higher temperature, but the mineralization rate constants were not affected by temperature. We also examined the effectiveness of six 40-day cycles of barley, canola, corn, oat, pea, soybean, and triticale at extracting N and phosphorus (P) from a Dark Brown Chernozem that had received 38 annual applications of manure at 180 Mg ha-1 yr-1 (wet wt.). Cereal grains and canola were more effective in extracting soil nutrients than the legumes. Nutrient phytoextraction was greater at when soil moisture was maintained at 100% than at 50% SFC. Partial least squares (PLS) regression analysis showed that soil properties measured in 2003 at the end of 30 yr of annual manure application adequately predicted barley grain yield for up to 7 yr following discontinuation of manure application. Our results indicated no evidence of convergence in barley grain yield among the manure treatments 7 yr after discontinuation of manure application, which reflects the high soil nutrient concentrations and the persistence EC effects.
Manure, Phosphorus, Dried distillers grains with solubes, Construction and demolition waste, Peat moss, phytoextraction, Partial least squares, Mineralization, Nitrogen